Hi. I'm no expert on Follis, but many French bikes used Sugino BB & cranks in the mid-70s, when the bike boom demand outstripped supply of Stronglight - the usual choice for French bikes. So, it is not impossible that this is original. You need to measure the axle length to see if it is a standard double, probably 114mm. If so, pretty much any of the vintage Stronglight, Campy, Sugino cranksets would fit.
That said, you should probably open it up to clean and regrease, anyway. This will give you a chance to measure more carefully, and to read what is on the spindle, itself. The photo barely shows, but it does seem to be French threaded. This limits options, but not impossibly. There's Velo Orane, Phil, or simply clean/repack and use this one. If it ain't pitted, it's probably just fine.
The one thing you need to check is the taper of the spindle. Bottom Brackets come in two flavours, ISO and JIS. ISO is used primarily for Campy and other European manufacturers, while JIS is for most of the Japanese component companies. I'd bet Sugino would be JIS.
That being said, many people have had success mixing the two different tapers, so it probably won't give you much trouble either way.
pull the spindle and measure, or look at the code that's probably stamped on the spindle. It'll be something like 3ss or 3t or 5 something. Google that, and you'll learn what the length is. IF you can find one, you can replace it with one that's a length more suited to your proposed crank. If you've got a french threaded bottom bracket, you can get a replacement cartridge unit in a number of lengths. If it's swiss (fixed side left-threaded), you're pretty much stuck to using what youv'e got, with perhaps a different spindle.